Authorities did not provide details about how the inmates died but said their autopsies are planned for Saturday.

The men were identified by the South Carolina Department of Corrections as Jason Kelley, 35; Jimmy Ham, 56; John King, 52; and William Scruggs, 44.

The prison has a history of violent incidents and deaths.

Last year, three correctional officers were fired after authorities said they stabbed an inmate four times in the torso. The officers were charged with attempted murder and misconduct in public office, CNN affiliate WIS reported.

In 2015, a 21-year-old man jailed at the prison died when he suffered a head injury. The coroner’s office determined that the injury was not caused by a fall, officials said in a statement.

A few months before, two inmates serving life sentences took two nurses hostage and held them with homemade knifes for about seven hours, according to CNN affiliate WACH.